Control mechanism for airplanes



Jan. 25, 1944. R. H. uPsoN CONTROL MECHANISM FOR AIRPLANES Filed Oct. 6, 1941 3 Sheets-Sheet 1 Jan. 25, 1944. R. H. uPsoN CONTROL MECHANISM FOR AIRPLANES 3 Sheets-Sheet 2 Filed Oct. 6, 1941 INVENTOR Faly fi Z/paam yfze e. ATTORNEYS.

Jan. 25, 1944. UpsoN 2,340,237

CONTROL MECHANISM FOR AIRPLANES I Filed Oct. 6, 1941 5 Sheets-Sheet 3 INVENTOR I f w? 7% ATTORNEYS.

Patented Jan. 25, 1914 iJNI'l'ED STATES PATENT OFFICE CONI'ROL MECHANISM FOR AIRPLANES Ralph H. Upson, Ann Arbor, Micln, assignor, by

mesne assignments. to Consolidated Vnltee Aircraft Corporation, a corporation of Delaware Application October 6, 1941, Serial No. 413,770

6 Claims. (Cl. 244 83) This invention relates to airplanes and particularly to the control thereof both in flight and upon the ground and has for its principal object the provision of an airplane and control mechanism therefor that contributes to the ease and safety in the control of the airplane both during flight and when running on the ground, obtained primarily by an improved grouping of control functions as pertaining to lift, steering, and braking respectively.

Objects of the invention include the provision of an airplane having ailerons and wing flaps and rudder and elevator surfaces together with a control member or column therefor connected thereto in a new and novel manner; the provision of a construction as above described in which the control member or column carries a control wheel connected to the ailerons and rudder surfaces for the simultaneous control thereof by turning of the control wheel about its axis, and the column is connected to the flaps and elevator surfaces for the simultaneous control thereof by bodily shiftable movement of the column in a forwardly and rearwardly direction; the provision of an airplane as above described in which the rudder surfaces comprise a pair of laterally spaced and separate rudder elements connected together for correlated movement in a new and novel manner; the provision of a novel form of mechanism for use between the control member of an airplane and the elevator and flap surfaces thereof; and the provision of a new and novel form of mechanism for adjustably loading the vertical flight control surfaces of an airplane tending to bias them toward a predetermined pivotal position.

. Other objects of the invention include theprovision of an airplane having a landing gear including two front wheels together with means for controlling the position of the front wheels relative to the longitudinal axis of the airplane for the purposes of controlling the path of movement of the airplane on the ground: the provision of a construction as above described including a novel i'orm of mechanism for controlling the steerable position of the ground wheels of an airplane; the provision of a construction as above described in which the brakes for the wheel or wheels on one side of an airplane are operable independently of the brakes for the wheel or wheels on the opposite side thereof: the provision of a construction as above described in which the wheel brakes are interconnected with the rudder means of the airplane whereby the actuation of the brake on one side of the airplane independently of the brakes on the opposite side thereof automatically actuate the rudder means to assist the brake means in turning the airplane while operating on the ground; the provision of a construction as above described in which the rudder means comprise a pair of separate rudders so constructed and arranged and connected with the brake control means that when all of the brakes are applied the rudders are swung in opposite directions to serve as wind brake means; the provision of a construction as above described in which the rudders are interconnected with the ailerons but are actuable independently of the ailerons during a braking application; and the provision of a control mecanism for airplanes that is simple in construction, efllcient inoperation and relatively economical to produce.

The above being among the objects of the present invention the same consists in certain novel features of construction and combinations of parts to be hereinafter described with reference to the accompanying drawings, and then claimed,

having the above and other objects in view.

In the accompanying drawings which illustrate a suitable embodiment of the present invention and in which like numerals refer to like parts throughout the several different views,

Fig. 1 is a plan view of an airplane includin a suitable embodiment of the present invention;

Fig. 2 is an enlarged, more or less diagrammatic, fragmentary perspective view illustrating the control mechanism for the fla-ps and ailerons of the airplane shown in Fig. i;

Fig. 2 is an enlarged, more or less diagrammatic. fragmentary perspective view illustrating the control mechanism for the flaps and ailerons of the airplane shown in Fig. 1;

Fig. 3 (sheet 2) is an enlarged, fragmentary, more or less diagrammatic perspective view illustrating the control mechanism for the rudders and ailerons and showing the connections between the steering wheels and the rudders and ailerons of the airplane shown in Fig. 1, together with the brake actuating means for the wheels:

Fig. 4 (sheet 1) is an enlarged fragmentary vertical sectional view taken approximately on the line 4-4 of Fig. l and illustrating the mechanism for controlling the steerable position of the front wheels;

Fig. 5 is an enlarged fragmentary horizontal sectional view taken on the line 5--5 of Fig. 4 and illustrating in greater detail the construction of that portion of the mechanism: and, v

Fig. 6 is a view similar to Fig. 3 but illustrating tion between the brakes and rudders. v A The primary fault in the-control system of the usual airplane, with respect to its use by novices, is the multiplicity of control functions that must be consciously coordinated toobtain best results.-

a modified form of brake mechanism and connec or more steerable ground wheels and particularly where suchground wheels are the front wheels. and in a further limited sense where the airplane "is provided with a pair of rudders. In abroad -sensetheterin elevator-ishereusedto denote any means of affecting the longitudinal trim or pitch- In this sense, although many of the controls ares mechanically separable, they mustbe considered turn the pilot flying a conventional airplane'must bank by means of the ailerons, at the same-time applying the rudder tomeutralize any skidding or slipping tendency, and if the turn is a sharp one he must simultaneously move the elevator upward in order to restore the turning component otherwise lost by reason ofthe banked position. This longitudinal turning component puts additional load upon the wings, which has frequently been known to result in a stall, the latter being likely to end in a spin particularly in case of poor coordination between the ailerons and rudder. With effective flaps this stalling tendency could be materially decreasedby partial flap deflection in proper proportion to the increased loading on the wings; but when the flaps are operated by the usual separate control it is hardly feasible to use it for such a purpose even on the part 01' an expert, let alone a novice, flyer. On the other hand, if the proper movement of ailerons, rudder. elevator and flaps is automatically coordinated and handled by a single control the facility and safety of flying can be greatly improved, especially if various supplementary controls such as ground and air braking means can be similarly coordinated.

The present invention has for its plu'pose the provision of an airplane and particularly a control mechanism therefor that not only will enhance the ease of handling an airplane both during flight and during movement upon the ground but will also eliminate certain features in the control of airplanes as heretofore constructed which offer a source of danger, particularly in the hands of unskilled operators. To that end a single manually operated control member, preferably in the form of a steering or control wheel, is interconnected with the ailerons and rudder means for simultaneous movement thereof upon turning movement of the wheel, and connected to the flaps and elevator surface or surfaces for simultaneous and correlated movement upon bodily shiftable movement of the steering wheel in forwardly and rearwardly directions. The airplane is provided with brakes for the wheels thereof and the control for the brakes is interconnected with the rudder means for simultaneous and correlated movement therewith. As a further feature in the preferred embodiment the airplane is provided with two laterally spaced front wheels which are steerable and connected to the control wheel for simultaneous movement therewith upon turning of the control wheel. It will, of course, be appreciated that the present invention is applicable to airplanes of different designs and constructions, that is, whether the airplane is of a monoplane or biplane type, whether it is of the type having the tail surfaces carried by an extension of the fuselage or by booms projecting rearwardly therefrom, whether controlled by a wheel or stick, and regardless of other detail features so long as it is provided with flaps and ailerons and rudder and elevator surfaces. In a more limited sense the invention is applicable to a type of airplane provided with one ing motion of. the aiiplanettheterm flap denotes 'any'means r elteri azthe. liftofthe wingwithoutjchanging 'thespeed, altitude orangleof at, tack {of the airplaneas a whole: the term ailerons denotes any-ineans-bficontrollingtherotation of the airplane aboutits maximums: axis; the-term rudder denotesany hcl nsof-controlling' the rotation-of theairplane about its vertical axis, and the term brake denotegany means of applying longitudinal drag to-the airplanewhether in the air or on the ground.

with the above in mind and now referring to the accompanying drawings, in Fig. 1 is illustrated an airplane of the monoplane type having a fuselage indicated generally at ll and oppositely disposed wings l2 each provided with an aileron l4 and a flap l6 pivotally mounted on the trailing edge thereof in a conventional manner. The fuselage Hl extends rearwardly and at its rear end pivotally supports thereon in a conventional manner an elevator surface I! and a pair of laterally spaced vertically upwardly projecting fins each pivotall supporting for movement about a vertical line at its rear edge a rudder 22. An engine (not shown) is mounted on the forward end of the fuselage l0 and enclosed in a conventional cowling 24 and is drivingly connected to a propeller 26 in a conventional manner. In accordance witha preferred form of the present invention the airplane is provided with a pair of laterally spaced front ground wheels 28 and a pair of laterally spaced rear ground wheels 30 suitably connected to the fuselage Ill.

One pair of the wheels 28-30 are mounted for steering movement to enhance the control of the direction of movement of the airplane on the round, and preferably these are the front wheels 28 in accordance with a more limited phase of the present invention. Preferably all of the wheels 28-30 are provided with braking means of suitable or conventional construction but in accordance with the present invention controlled in a novel manner which will hereinafter be more fully described. To enable the pilot to control the various control surfaces of the airplane a vertically directed lever or control column 36 is mounted in the cockpit for pivotal movement in a vertical plane about a horizontal axis. As best illustrated in Fig. 2 the column 36 is provided with a cross-bar 38 fixed thereto a short distance above the lower end thereof and each end of the cross-bar 38 in turn has fixed thereto a link 40 which extends upwardly therefrom. The links 40 are connected by suitable pivot pins such as 42, arranged with their axes aligned and in a horizontal plane extending spanwise of the airplane, to a suitably fixed part of the fuselage, thereby mounting the. column 86 for the movement described. At its upper end the lever 36 rotatably supports therein the push and pull shaft 44 which is arranged with its axis in a vertical plane parallel to the longitudinal center line of the airplane and preferably in approximately perpendicular relationship with respect to the axis of the column 38. The shaft 44 is, of course, held against axial movement relative to the column 36. At its rear end the upper end of the column 36 preferably encloses the shaft 44 between the column 36 and the control wheel 46. The column 36 is thus mounted for pivotal movement about the pins 42 and its pivotal movement may be controlled by the operator grasping the control wheel 46 and pushing it forwardly or pulling it rearwardly from a central or neutral position. Turning of the wheel 46 rotates the shaft 44 as will be appreciated.

The bifurcated forward end of a link 56 is pivotally connected as at 52 to the lower end of the column 36 at a material distance beelow the axis of the pivot pins 42. The rear end of the link 56 is also bifurcated and pivotally secured thereto as at 54. Within such bifurcation is a plate-like member 56 which projects both below and above its pivotal connection 54 with the link 56. The plate member 56 is pivoted by pins as at 51 approximately midway its height about a fixed horizontal axis extending spanwise of the airplane. A push-pull rod 58 has one end thereof secured to the lower end of the member 56 and extends rearwardly therefrom and is connected to the lower end of'a horn member '92. The horn shaft 96 being rotatable about a fixed axis, it will be appreciated that pivotal movement of the column 36 about the axis of its pivot pins 42 causes pivotal movement of the plate member 56 about the pivot 51 and similar movement of the horn 92. Means are provided in accordance with the present invention tending to bias the member 56 in either direction of rotation about its pivotal axis 51 and to effect this result the following construction is provided. Rearwardly of the member 56 a hand lever 66 is mounted for pivotal movement about a horizontal, spanwise directed pivotal axis 68 located between its ends. A cable 16 connected to the upper end of the member 56 extends rearwardly therefrom and passes over a sheave 12 rotatable about a fixed axis and is then connected to the rear end of a tension spring 14 the forward end of which is connected to the lower end of the lever 66. The tension of the spring 14 thus constantly acts upon the member 56 tending to rotate it in aclockwise direction of movement, as viewed in Fig. 2, about its pivot point 51. A secnd tension spring 16 is connected at its forward end to the lever 66 above the pivot point 68 of the latter and at its rear end is connected to a cable 18 which passes over a sheave 86 rotatable about a fixed axis and then extends forwardly where it is connected to the upper end of the member 56 but at a point forwardly of the point of connection with the cable 16 therewith. In thus passing forwardly the cable 18 passes under a convexly curved block 62 fixed to the side of the plate member 56 and arranged with its curved face directed downwardly and forwardly. The block 82 is so arranged that the pivotal axis 51 of the plate member 56 lies within or at least close to the curve of the block 62 so that the effective point of connection of the cable 18 and the plate member 56 is slightly below the pivotal axis of the latter when the column 36, and therefore the plate member 56, are in their normal or neutral positions. The pivot 51 is, however, in relatively close proximity to the curved face of the block 62 and the curvature of the block is much greater than that of a circle of a radius equal to the shortest distance of the curved face of the block from the pivot point 51, so that the effective point of connection of the cable 18 with the plate member 56 moves downwardly and away from the pivotal axis 51 when the plate member 56'pivots in a counterclockwise direction of movement materially away from its normal or neutral position as shown. It will thus be appreciated that the force of the springs 14 and 16 act on the plate member 56 to tend to turn it in opposite directions of rotation. The spring 14 being directly connected to the upper end of the plate member 56 acts through a greater leverage on the plate member 56 than the spring 16 and consequently where the springs 14 and 16 exert the same pull the spring 14 exerts a superior turning force on the plate member 56. The force of the spring 16 with the arrangement described is, of course, at a minimum when the plate member 56 is in its normal pivotal position shown but, as will be appreciated, its effect is increased whenever the plate member 56 is pivoted in a counterclockwise direction of rotation as viewed in Fig. 2 beyond its normal or neutral pivotal position shown. Preferably the curvature of the curved face of the block 62 is such as to increase the effective pull of the spring 16 on the plate member 56 along a parabolic curve as the plate member rotates in a counterclockwise direction of movement from the po ition shown.

For the purpose of simplicity in description and drawings the plate member 56 is shown connected by the rod 58 with the elevator l6 and only one of the ailerons l6, it being understood that equivalent means may be employed for connecting the plate member 56 to the remaining flap, and the preferred method of accomplishing this will be later described. While the control column 36 may be connected to the elevator l8 and flap l6 in any suitable manner to provide simultaneous movement of these control surfaces in opposite directions of rotation as previously mentioned, one suitable method which is shown in Fig. 2 by way of illustration is as follows.

The outer end of the shaft 96, linked to the control column 36 by means already described, has fixed thereto a bellcrank including an upwardly extending arm 94 and a downwardly and rearwardly extending arm 96. The upper free end of the arm 94 is connected by a rod or link 98 with the free end of a horn I66 fixed to the elevator 18 and projecting downwardly below the pivotal axis I62 theretof. The free end of the arm 96 is connected by a link I64 with the lower free end of a horn I66 fixed to the flap l6 and extending downwardly below the pivotal axis I66 thereof.

With this construction it will be appreciated that when the control column 36 is pulled rearwardly by the pilot the plate member 56 will be caused to rotate in a clockwise direction of rotation as viewed in Fig. 2 thus causing the rod 58 to move forwardly, thus rotating the shaft 96 in a direction to move the upper end of the bellcrank arm 94 rearwardly and the lower end of the arm 96 thereof downwardly and forwardly, this movement of the bellcrank causing the elevator l8 to rotate in a counterclockwise direction as viewed in Fig. 2, that is to raise its trailing edge, and causing the flap l6 to rotate in a clockwise direction of rotation as viewed in Fig. 2, that is to lower its trailing edge. Conversely if the control column 36 is pushed in a forwardly direction the consequent movement of the related parts as above described will cause the trailing edge of the elevator l8 to be depressed and the trailing edge of the flap l6 to be raised.

It will be noted that because of the fact the ment of the control column 36 or wheel 46 either forwardly or rearwardly from its normal or neutral position will effect a maximum pivotal movement of the elevator I3. On the other hand, ,bea cause the arm 96 of the bellcrank extends 'not only downwardly and rearwardly and the horn I66 on the flap I6 is arranged in approximately perpendicular relationship with respect to the general plane of the flap I6, when the control wheel 46 is pushed forwardly, as for instance to put the plane into a dive, a relatively minor amount of pivotal movement will be imparted to the flap I 6 and the relative amount of pivotal movement of the flap I6 as compared to the pivotal movement of the control column 36 will decrease as the control column 36 is pivoted forwardly out of its neutral position. On the other hand, if the control wheel 46 is pulled rearwardly from its normal position the initial downward movement of the flap I6 will be relatively small but as the pivotal movement of the control column 36 continues rearwardly from its normal or neutral position the arm 96 will more nearly approach a vertical position and thus will increase the relative pivotal movement of the flap I6 with respect to the corresponding pivotal movement of the control column 36. This arrangement of parts provides a construction in which when the control column is moved to cause the airplane to descend the flap I6 will move very slightly out of its normal or neutral position. When the control column 36 is moved to raise the elevator I6, as occurs as an incident to normal flight or when it is desired to cause the airplane to climb, then the flap I6 will be depressed only slightly during the first movements of the control column in this direction, so as to Offer very little added drag at those times of movement of the elevator I8 is required for normal flying control, but will be depressed to a rapidly increasing extent when the control column 36 is pivoted rearwardly out of its neutral position to the extent required for instance in landing or in similar conditions requiring increased lift and drag of the wings. This particular inter-relation of relative movements of the elevator and flap forms no part of the present invention but does form part of the subject-matter of my co-pending application for Letters Patent of the United States for improvements in Airplane, filed July 18, 1941, and seriallynumbered 403,047. The combination of such a flap control with separately operable aerodynamic brakes or air drag means is, however, new and important because when flap deflection is made a normal part of the routine control it should obviously be designed to ofl'er a minimum of drag. Yet for some conditions, such as landing over obstructions, high drag is desired. Hence, instead of the high-drag flap commonly used, this invention employs a lowdrag flap, and separate drag control, preferably using the rudders for this purpose as will later be made clear.

In the case of two flaps being used, the remaining flap, similar to I6, on the opposite side of the airplane may be controlled by providing an extension of the shaft 90 having an arm or lever equivalent to the arm 96 connected to such flap in the same manner as the flap thus described. As will be appreciated the remaining flap will thus, or b any equivalent means, be caused to move in exact accordance with the movement of the flap I6 first described.

From the description of the control of the flaps l6 and elevator I8 above given the effects of the bungee springs I4 and I6 on such control will now be more apparent. In the main it will be appreciated that the combined effect of these springs is to urge the various connections towards a position in which the trailing edge of the flaps I6 will be depressed. It will, of course, be ap-- preciated that when the trailing edges of the flaps I6 are depressed the force of the wind flowing against the under surfaces thereof as well as the suction exerted against the upper surface thereof is in a direction tending to move the flaps more nearly into alignment with the associated wing, and such force must be resisted by the pilot through the control column 36. By the use of a bungee spring or springs the load thus imposed on the pilot may be materially reduced.

It would, of course, be undesirable to so arrange such bung ee spring or springs that when the plane is in normal flight the pilot would be required to exert a material eifort to maintain the flaps in aligned relation with respect to the wings. For that reason, in accordance with the present invention, the anchorage for the bungee springs I4 and I6 is made adjustable so that the efiect thereof on the flaps may be varied to suit particular conditions of flight. For instance, where a pilot is about to land the plane, under which conditions he will desire the flaps l6 to be depressed to a maximum amount, he may operate the lever 66 to pivot it in a clockwise direction of rotation as viewed in Fig. 2 to thereby increase the tension of the spring I4 and decrease the tension of the spring I6, the tension of the spring I4 thus being increased to aid the pilot in maintaining the trailing edge of the flaps I6 depressed. In normal flight the pilot may adjust the lever 66 to so proportion the respective forces of the springs I4 and I6 on the plate member 56 as to tend to maintain the pivotal positions of the flaps I6 in a desired relation with respect to the general plane of the associated wings, but at the same time permitting the full desired range of control without the exertion of excessive manual force even when the adjustment of lever 66 remains unchanged. Whether movement of the flaps I6 under such conditions is desired or not. when the pilot operates the control column 36 to move the trailing edge of the elevator upwardly, the force of the spring I4 decreases; but the force of the spring I6 tends to increase and would put an excessive restraint on the pivotal movement of plate member 56 were it not for the decreasing lever arm afforded by the curved block 62. Conversely, when the trailing edge of the elevator I8 is depressed and the force of the spring I4 is increased under such circumstances,

' the force of the spring I6 is decreased, but its turning moment on the plate member 56 is affected to a relatively minor extent as under such conditions the effective arm of the spring force is increased by the rotation of the block 82.

that the pilot may offset to a large extent the pressure of the air acting upon the flaps, when they are in depressed condition, tending to move them into alignment with their associated wings.

and such that the forces resisting movement of the flaps from a desired adjusted position is more or less automatically compensated for when the flaps are moved out of such position through operation of the control column.

The control for the ailerons and rudders is illustrated in Fig. 3. As there indicated, the shaft 44 immediately forwardly of the control column 36 is provided with a sprocket IIO fixed thereto. Trained over the sprocket H is a chain II2. One end of the chain II2 is connected to the end of a flexible cable H4 and the opposite end of the chain is connected to the end of a flexible cable H6. The cables H4 and H6 extend downwardly from the sprocket H0 and cross each other. the cable I I4 passing under a sheave H8 and the cable II6 passing under a sheave I20. The cable II4 extends rearwardlyand is connected to a plate I22 and the cable I I6 extends rearwardly in approximately parallel relation with respect thereto and is there connected to a similar plate I24. Connected to and extending rearwardly from the plate I 22 are a-pair of cables I26 and I28 and connected to and extending rearwardly from the plate I24 are a pair of cables I30 and I32. The cables I26 and I28 pass under a double sheave I34 and then extend upwardly therefrom, the cable I26 then passing over a sheave I36 and then in a spanwise direction to the left as viewed in Fig. 3. The cables I30 and I32, similar to the cables I26 and I28, pass under 2. double sheave I 38 and then extend upwardly, the cable I 30 passing over a sheave I40 corresponding to the sheave I36 and then spanwise of the airplane in the opposite direction from the cable I26. The cable I28 extends upwardly from the sheave I34 and then over a sheave I42 and then in the same general direction as the cable I30. The cable I32 extends under the sheave I38 and then upwardly over a sheave I44 and then in the same direction as the cable I26.

Each aileron I4 is pivoted for movement about an axis I50 and each aileron at its inner end is provided with an upstanding horn I52 fixed thereto. Forwardly of the inner end of each aileron I4 a double armed lever I54 is pivotally mounted I on the associated wing I2 for movement about a vertical axis fixed with respect to such wing. Each lever I54 is provided with an upwardly extending hub portion I56 to which is fixed an outwardly extending arm I58 arranged in generally perpendicular relationship with respect to the longitudinal center line of the lever I54 but preferably forwardly inclined with respect thereto as indicated. The outer or free end of each arm I58 is connected by a link I60 with the free end of the horn I52 on the corresponding aileron I 4. The outer end of the cable I26 is fixed to the outer end of the forwardly extending arm of the corresponding double armed lever I54 and the corresponding end of the cable I32 is fixed to the free end of the rearwardly projecting arm of the same double armed lever I54. Similarly the outer free end of the cable I30 is fixed to the outer free end of the forwardly extending arm of the double armed lever I54 on the right as viewed in Fig. 3, and the corresponding end of the cable I28 is fixed to the free end of the rearwardly projecting arm of such double armed lever.

With the above described arrangement it will be appreciated that turning of the control wheel 46 will cause rotation of the sprocket II 0 and consequent longitudinal travel of the cables H4 and I I6 in opposite directions, such movement of the cable I I4 being imparted to the cables I26 and I28 and such movement of the cable I I6 being imparted to the cables I28 and I30. The movement of these cables will cause rotation of the double armed levers I54 in opposite directions and the latter, being connected as described to the ailerons I4, will cause. them to be pivoted about their axes I50 in opposite directions of rotation. In view of the fact that the cables H4 and II 6 are crossed, rotation of the steering wheel 46 in a counterclockwise direction of rotation as viewed by the pilot operating the same will thus cause a depression of the righthand aileron I4, as viewed by the pilot, and raising of the righthand aileron I4. Conversely, movement of the steering wheel 46 in the opposite or clockwise direction of rotation will cause the lefthand aileron I4 as viewed by the pilot to be depressed and the righthand one thereof to be raised. By inclining the arms I58 in a backward direction, it will be appreciated that there will be a greater raising movement of one aileron than there will be a depressing movement of the opposite aileron for an equal movement of the control wheel 46 under the above described circumstances.

The rudders 22, as previously explained, are laterally spaced from one another and each is mounted for rotation about a corresponding fixed vertical axis I 10. Each rudder 22 has fixed thereto near its axis a laterally projecting double horn I12. The inner arm of each horn I12 has fixed thereto a cable I14, and each cable I14 extends forwardly and around a sheave I16. After passing over the sheave I16, the forward ends of the cables I14 are connected to the opposite ends of a tension spring I18 which thus serves with the cables I14 to operatively interconnect the two rudders 22. The spring I18 is maintained constantly under a tension in order to maintain the operativeness of the rudder control as will hereinafter be more apparent.

The free end of each outer arm of the double armed levers I12 has fixed thereto the rear end of a forwardly extending cable I80, the forward end of each of which is fixed to a yoke I82 between the arms of which a sheave I84 is rotatably supported. A cable I86 is trained over each of the sheaves I84. One end of the cable I86, to the right as viewed from the pilot's seat, is fixed to the cable II4 rearwardly of the sheave H8, and the corresponding end of the cable I86, to the left as viewed from the pilots seat, is correspondingly fixed to the cable II6. On the opposite side of the sheaves I84 each cable I86 extends forwardly each under a corresponding sheave I92, then over a corresponding sheave I94 from which it turns rearwardly and its end is fixed to a suitable point of anchorage such as I96 and which may be of any suitable part of the fuselage of the airplane.

For the moment it may be assumed that the sheaves I94 are mounted to rotate about a fixed axis in which case it will be appreciated that when the control wheel 46 is turned to cause lower runs of the cables I I4 and I I6 to move longitudinally of the airplane in opposite directions, such movement of the cables H4 and H6 will cause an equal movement of those ends of the cables I66 fixed thereto and will, therefore, vary the positions of the sheaves I84 longitudinally of the airplane and in opposite directions of movement. Movement of one sheave I84 in one direction and the other in the opposite direction acts through the cables I to turn the rudders 22 in a similar direction of rotation about their pivotal axes I10. For instance, when the hand wheel 46 is turned in a clockwise direction of movement as viewed from the pilots seat, as previously explained the lower run of the cable I I8 will move rearwardly and that of the cable II4 forwardly,

causing the righthand aileron I4 as viewed from the'pilots seat to be lifted and the lefthand aileron I4 to be depressed. The forward movement of the cable H4 and rearward movement of the cable II8 under such conditions will pull the righthand sheave I84 as viewed from the pilot's seat forwardly and will permit the lefthand one thereof to move rearwardly, thus causing the rear edges of the rudders 22 under such circumstances to swing to the pilot's right, thus cooperating with the ailerons I4 to turn the plane to the right. The reverse of such movements will, of course, occur when the control wheel 48 is turned in a counterclockwise direction of rotation as viewed from the pilot's seat. It will, of course, be appreciated that when one of the cables I80 is thus pulled and the rudder on the same side deflected outwardly, the tension of the spring I18 acting through the cables I14 will turn the opposite rudder inwardly and take up the cable slack that would otherwise form on that side.

The front wheels 28 and the rear wheels 30, if desired, are equipped with suitable brakes. While the particular type of brakes employed is unimportant as far as the present invention is concerned, it is assumed in the present case for the purpose of illustration that the brakes are of the conventional hydraulically actuated type wherein a wheel cylinder 200 is carried by each wheel and is actuable to expand the braking elements for such wheel. The wheel cylinders 200 are, of course, expanded through the medium of a master cylinder mechanism actuated by a pedal mechanism under the control of the pilot and, in the broader aspects of the invention, an individual pedal and a master cylinder may be provided for the brakes on each side of the airplane as illustrated in Fig. 3 or a single pedal and single master cylinder may be provided for all of the brakes as illustrated in Fig. 6, or a single master cylinder may be equally operable by either or both of two pedals.

In the construction illustrated in Fig. 3, two laterally spaced brake pedals 202 are mounted for pivotal movement about an axis 204 fixed with respect to the airplane and extending horizontally spanwise of the airplane. has a downwardly extending arm 208 which is connected with the push rod 208 of the corresponding master cylinder 2I0. Each master cylinder 2I0 is provided with a conduit 2I2 connecting it with the wheel cylinder 200 for the front wheel on the corresponding side of the airplane. If it is desired that the rear wheels 30 also be braked, then a branch such as 2 for each conduit 2I2 may be extended to the wheel cylinder for the wheel 30 on the corresponding side of the airplane as will be readily appreciated. A suitable stop, such for instance as 2I8, is preferably associated with each brake pedal 202 as by engagement with the downward extending arm 208 thereof, as shown, to limit the rearward movement of the upper end of each pedal 202. As will be appreciated, by the arrangement shown and described the brakes on either side of the airplane may be actuated by depressing the corresponding pedal 202 therefor, or all of the brakes may be simultaneously actuated by simultaneously depressing both pedals 202.

In accordance with one phase of the present invention each brake pedal 202 has fixed for rotation therewith an upwardly extending arm 220 the upper end of which carries a yoke 222 with- Each pedal 202 in the corresponding sheave I84 previously described is rotatably mounted. When the brake pedals 202 are in their inoperative or rearward positions the sheaves I84 are thus anchored against rearward movement. Thus for all nor mal control movements of the ailerons I4 and rudders 22 during flight, the sheaves I84 may be assumed to rotate about fixed axes and the correlated movements of the ailerons I4 and 22, as previously described, upon rotation of the control wheel 48 results.

However, it will be appreciated that when one of the pedals 202 is depressed independently of the other, it will draw its corresponding sheave I84 forwardly and in so doing will act through its corresponding cable I88 to draw the corresponding sheave I84 forwardly and thereby pull the corresponding cable I forwardly without.

however, resulting in any longitudinal movement of the remaining cable I80. Under such conditions the cable I00 which is drawn forwardly will serve to rotate the corresponding rudder 22 about its axis "0, the spring I18 stretching under such conditions to permit such pivotal movement of the one rudder without a corresponding movement of the other. For instance, if the righthand pedal 202 as viewed from the pilots seat is depressed the rudder 22 on the corresponding side of the airplane will be swung to bring its trailing edge outwardly away from the center line of the airplane. This is of advantage when the airplane is rolling on the ground for in such case the braking of the righthand wheel or wheels only will ordinarily be for the purpose of turning the airplane to the right and such movement of the righthand rudder 22 will assist such turning movement under such conditions. The reverse of the above described operations will, of course, be true. In other words, if the lefthand brake pedal 202, as viewed from the pilot's seat, is depressed instead of the righthand brake pedal, the rudder 22 on the lefthand side of the plane as viewed from the pilot's seat will swing outwardly or to the left under such conditions with simultaneous braking of the wheel or wheels on the lefthand side of the airplane.

If both brake pedals 202 are depressed simultaneously, then both cables I80 will be pulled forwardly and both rudders 22 will be swung outwardly, this movement of the rudders in such case conditioning the rudders to act as air brakes cooperating with the wheel brakes to assist in bringing the airplane to a stop. Under some circumstances, as for example to control the glide path or restrict diving speed, such braking effect on the airplane in flight is desirable, under which conditions simultaneous depressing of both of the brake pedals 202 will swing both rudders 22 outwardly to effect this result.

It wil also be appreciated that the depression of either one or both of the brake pedals 202 will have no effect on the positions of the ailerons I4 for any constantly held rotatable position of the control wheel 48. Turning of the control wheel 48 not only will cause the usual movement of the ailerons I4 but will also act to turn the rudders 22 in a direction as determined by the direction of rotation of the control wheel 48 from the position initially determined by the depression of the pedal or pedal 202 and in a direction corresponding to that which would normally occur by operation of the control wheel 48 only. In other words if one brake pedal 202 is depressed to cause the corresponding rudder 22 to swing outwardly and then the control wheel 48 is turned, the remaining rudder 22 will turn as under normal circumstances while the rudder first actuated by the depression of the pedal will turn in a corresponding direction from the position initially determined by the application of the brake pedal. Depressing one pedal, however, will introduce a force in the control system tending to bias the control wheel in a direction opposite to the initial rudder application. If both brake pedals have been depressed and the hand wheel 46 is rotated, both of the rudders will be turned from the position initially determined by the application of the brake pedals in the direction determined by the movement of the control wheel 46. Accordin ly, even though both brake pedals are depressed during flight a measure of lateral control still remains through turning of the control wheel 46, not only from the movement of the ailerons l4 but also, through movement of the rudders 22 themselves.

The ground wheels 28 and 38 may be mounted on the airplane in any conventional manner but in accordance with a further phase of the present invention the front wheels 28 are made steerable so as to facilitate controlling of the movement of the airplane on the ground. One suitable method for accomplishing this is illustrated in Figs. 2, 4 and 5 from which it will be noted that the fuselage I8 adjacent the forward end thereof is provided at each side thereof with a bracket 24!] fixed thereto. A leg 242 is pivotally secured at its upper end to each bracket 240 by means of a pivot pin 244 and extends downwardly and laterally outwardly therefrom. Any suitable or conventional type of yieldable means may be provided for urging the legs 242 towards their normal position or otherwise to enable the legs 242 to absorb shock upwardly upon impact of the wheels with the ground or the like.

The lower end of each leg 242 is provided with a pair of outwardly directed vertically spaced portions 246 between which extends and to which is fixed a vertically directed pivot pin 248, best shown in Fig. 5. Rotatably mounted upon each pivot pin 248 between the corresponding portions 246 is a knuckle member 258 and each knuckle member 250 is provided with an outwardly directed spindle 252 upon which the corresponding wheel 28 is rotatably mounted. As best illustrated in Fig. 5 each knuckle member 258 has fixed thereto an inwardly extending form wheel segment 254. The worm wheel segment 254 lies in mesh with a worm 256 fixed to a shaft 258 projecting horizontally in a forwardly and rearwardly direction through the lower end of the corresponding leg 242 and is rotatably mounted in such leg by bearings 260 carried thereby. The rear end of each shaft 258 projects rearwardly from the corresponding leg 242 and has fixed thereto the sprocket 262. It will be appreciated that by rotating the sprocket 262 the associated worm 256 will be rotated and acting through the cooperating worm wheel segment 254 will turn the corresponding knuckle member 250 and consequently moves the corresponding wheel 28 in a steering direction about the axis of the associated pin 248. As shown in Fig. 4 the pivot pin 244 connecting each leg 242 with its bracket 248 also serves to support thereon a pair of sheaves 264.

As best illustrated in Figs. 2 and 4 the control column 36 a short distance above the crossbar 38 thereof has fixed thereto a forwardly projecting pin 266 upon which four sheaves 268 are rotatably mounted. The shaft 44 forwardly of the sprocket H8 thereon has fixed thereto a pair of sprockets 218. Over each sprocket 218 an endless chain 212 is trained. As illustrated in l igs. 2 and 4 the chain 212 trained over the forward sprocket 210 passes downwardly with the runs thereof passing under the two forward sheaves 266 and then to the right, as viewed from the pilot's seat, over the lefthand sheav 264 illustrated in Fig. 4, and then downwardly over the sprocket 262 at the lower end of the lefthand leg as viewed in Fig. 4. Similarly the chain 212 trained over the rearwardmost sprocket 216 extends downwardly under the two rearmost sheaves 268, then over the righthand sprocket 264 as viewed in Fig.- 4 and then over the sprocket 262 at the lower end of the righthand legillustrated in Fig. 4. By this arrangement the sprockets 218 are connected with the sprockets 262 and the operativeness of th connection is maintained regardless of pivotal movement of the legs 242 about their pivot pins 244 and regardless of pivotal movement of the control column 36 about its pivotal axis 42. The arrangement is, of course, such that when the control wheel 46 is turned in a clockwise direction of rotation as viewed from the pilot's seat the wheels 28 will be turned to direct the airplane to the right, and when turned in a counterclockwise direction of rotation will be turned to direct the airplane to the left, in a manner similar to the results obtained by turning the steering wheel of the motor vehicle.

The abov described movement of the front wheels 28 for steering purposes is, of course, automatically tied in with the movement of the ailerons I4 and rudders 22 for controlling the lateral direction of movement of the airplane ni flight. The same movement of these surfaces. with or without aid through braking of the wheels on one side of the airplane or the other, are of advantage in controlling the direction of movement of the airplane on the ground. Thus the turning of the front wheels 28 is of no disadvantage during flight, and the turning of the ailerons' and rudders is an advantageous adjunct of the steering movement of the front wheels 28 when the airplane is running along the ground.

The consideration of wheel arrangement is also tied in with the longitudinal control coordination previously described. The so-called tri-cycle gear, with a single wheel forward, in its usual arrangement has its main or rear wheels only slightly behind the center of gravity of the airplane. This is because in taking off with the normally controlled airplane it is necessary for lift to depress the tail, thus rotating the entire airplane around its rear wheel contact line. With the coordinated flap and elevator movement on the other hand, enough lift at the moment of take-off can be had by means of the flap deflection alone, to justify placing the main wheels substantially further back than would otherwise be feasible. Were it not for this Or some equivalent means of obtaining take-off lift the use of two front wheels would hardly be justifiable because so little load wouldrest on them; yet by having two front wheels instead of one, under the conditions here described, improved ground stability is obtained and mor positive steering.

Such flap control for take-off purposes should b directly coordinated with the elevator so that when the airplane becomes air supported the elevator, as well as the flap, is in a position to hold the desired climbing attitude. At the same time, the simple coordinated control permits even a novice to hold both the fiap and elevator in their minimum drag positions until they are needed for actual take-off. The process is further An advantage of employing the front wheels v 28 for steering purposes rather than the rear wheel or wheels, as is conventional practice, is that it makes it much easier for the pilot to dodge obstructions on the ground in that it moves the nose of the airplane away from the obstruction rather than pulling the tail over into a position where it might hit the obstruction. Furthermore, where the airplane in landing and in running along the ground is caught by a side gust of wind, the steerability of the front wheels enables the pilot to bring the airplane into the wind quicker and the reaction of the wind on the wings makes the airplane more quickly responsive in righting itself than in cases where it is attempted to' swing the tail around to control such movements.

As previously mentioned instead of employing two brake pedals as illustrated in Fig. 3 and a separate master cylinder for each, it is possible to employ a single brake pedal and a single master cylinder and still obtain many of the advantages obtained by the dual construction with a further gain in the simplicity of control. The use of the single pedal and single master brake cylinder is illustrated in Fig. 6 in which the only change is in connection with this feature. Accordingly, in Fig. 6 all of the parts corresponding to the parts illustrated in Fig. 3 are illustrated by the same numerals and a specific description of each thereof is, therefore, unnecessary. Referring to Fig. 6 it will be noted that instead of employing a pair of master brake cylinders 2th a single master brake cylinder U is employed which may be identical to the master cylinder 2|. previously described except possibly being desirably of slightly larger capacity. Conduits 2| 2 extend from the master brake cylinder 2N to the wheel cylinders 20. for both front wheels 28 as well as to the rear wheel brakes when employed. -A'sirigle brake pedal 280 is employed in this case plvotally mounted about a horizontal and spanwise directed axis 282. The pedal 280 is provided with a downwardly extending arm 2" equivalent to the arms 206 previously described and cooperating with a suitable fixed stop 2 It for limiting rearward movement of the pedal 2". In this case the pedal 280 has fixed thereto for equal rotation therewith a pair of upwardly extending arms 220' each of which carries at its upper end a sprocket I94, which sprockets I84 may be the same sprockets previously described and which receive the corresponding cables 186. As will be readily appreciated with this modified form of construction depression of the brake pedal 280 will cause simultaneous application of the brakes on both sides of the airplane through actuation of the master cylinder 2W. Thus it is not possible with this construction to apply the brakes on one side of the airplane independently of those on the other. Furthermore with the construction illustrated in Fig. 6 any brake application through depression of the brake pedal 2" will cause simultaneous outward and opposed movement of the trailing edges of the rudders 22. Turning of the control wheel 46 will cause like pivotal movement of the rudders 22 about their pivotal axes regardless of whether or not they have previously been moved away from each other by depression of the brake pedal 280. It will also be appreciated that with the construction illustrated in Fig. 6 one rudder 22 cannot be turned independently of the other rudder 22 during the brake application as is possible in the construction illustrated in Fig. 3. The remaining advantages of construction illustrated in Fig. 3 are, of course, present in the construction illustrated in Fig. 6.

Having thus described my invention what I claim by Letters Patent is:

1. In an airplane, in combination, a fuselage,

a pair of legs pivotally secured to said fuselage and directed downwardly therefrom, a knuckle member pivotally mounted on the lower end of each of said legs for movement about a vertically extending axis, a spindle on each of said knuckle members, a wheel rotatably mounted upon each ,of said spindles, a gear segment fixed to each of said knuckle members. a worm rotatably carried by each of said legs in meshing engagement with the corresponding one of said gear segments, a sprocket fixed to each of said worms for equal rotation therewith, a rotatable control member, a pair of sprockets fixed to said rotatable control member for equal rotation therewith, and endless power transmission means connecting one of said last mentioned sprockets with oneof said first mentioned sprockets and the other of said last mentioned sprockets with the other of said first mentioned sprockets.

2. In an airplane, in combination, a pair of pivotally mounted rudders, yieldable means interconnecting said rudders, a single control member, means interconnecting said control member and said rudders operable to cause pivotal movement of said rudders in the same direction about their pivotal axes, pedal operated means cooperable with the last mentioned means operable to cause yielding of said yieldable means and relative movement of said rudders in opposite directions of movement about their pivotal axes, a steerable supporting wheel adapted for ground :ontact, means interconnecting said control member with said wheel for effecting steering movement thereof, a brake for said wheel, and a connection between said pedal operated means and said brake for applying said brake.

3. In an airplane, in combination, a pair of pivotally mounted rudders, means including a yieldable element operatively connecting unlike sides of said rudders, a movable control member, a pair of linearly movable means interconnecting said control member with the remaining sides of said rudders and movable by said control means in opposite directions of movement to eflect turning movement of said rudders in the same direction of rotation about their pivotal axes, ground wheels including a wheel steerable by means of said control member, braking mean for said ground wheels, pedal means for controlling said braking means, and means interconnecting said pedal means with said linearly movable means operable to effect movement 01' said linearly movable means independently of movement of said control member.

4. In an airplane, in combination. a pair of pivotally mounted laterally spaced rudders, means including a yieldable element operatively connecting unlike sides of said rudders, a movable control member, a pair of linearly movable means interconnecting said control member with the remaining sides or said rudders and movable by said control means in opposite directions of movement to eflect turning movement of said rudders in the same direction oi rotation about their pivotal axes, ground wheels including a wheel steerable by means of said control member, braking means for said ground wheels, pedal means for controlling said braking means, and means interconnecting said pedal means for simultaneous movement with both oi said linearly movable means whereby to effect movement of the latter in the same direction independently of movement of said control member.

5. In an airplane, in combination, a pair of pivotally mounted laterally spaced rudders, means including a yieldable element operatively connecting unlike sides of said rudders, a movable control member, a pair of linearly movable means interconnecting said control member with the remaining sides or said rudders and movable by 1 said control means in opposite directions of movement to effect turning movement of said rudders in the same direction of rotation about their pivotal axes, ground wheels including a pivotally mounted wheel forward of the center of gravity, braking means for said ground wheels, a pair of brake pedals, means operatively interconnecting each of said brake pedals with the braking means on the corresponding side or said airplane, and

means interconnecting each of ms brake pedals with that one of said linearly movable means ex- 10 interconnecting said control member and said rudders tor eil'ecting simultaneous movement oi said rudders in the same direction about their pivotal axes, means connecting said control member and said ground wheels for efl'ecting steering 15 movement or said ground wheels simultaneously with movement oi said rudders in the same direction of movement about their pivotal axes, a pair of .brake pedals, means operatively connecting said brake pedals with the braking means for said 20 wheels, means connecting one of said pedals with one 01 said rudders, and means connecting the other 01' said pedals with the other 0! said rudders, the last two mentioned means being operative to efiect movement 01 said rudders upon movement 25 oi the corresponding of said pedals independently of movement of said control member.

RALPH H. urson. 

